1. Field of the Invention
This invention relates to data storage medium and data read and write apparatus for use in a computer, and more particularly, this invention relates to magnetic and optical cards and card readers.
2. Description of the Related Art
The external storage that has come to be widely used is divided into three major categories: the integrated circuit (IC) memory such as ROM or RAM which is being extensively applied in the field of semiconductors, the magnetic disk drives and magnetic tape drives using the techniques of magnetic recording such as hard disks or floppy disks, and optical recording techniques that include compact disks (CDs), write-once optical disks, and re-writable optical disk drives and magneto-optic disk drives. All these apparatuses feature large storage capacity and random access capability except the magnetic tape drive.
Magnetic card reader and optical card reader are the major card readers in use. Rectangular cards, which are about the size of a business card, have several longitudinally arranged recording tracks. Unlike the magnetic disk drive with which data can be repeatedly read because of the circular recording tracks, conventional card reader is disadvantageous in that data on a given track cannot be accessed repeatedly due to its linear tracks, e.g., each single track is cut off at both ends.
FIGS. 120A to 120C give general description of a conventional magnetic card. FIGS. 120A and 120B are a sectional view and a top view of a magnetic card whose surface is covered with magnetic material entirely and FIG. 120C shows another type of a magnetic card which is coated with magnetic material only partially. Underneath board 1001 are magnetic film 1002, protective layer 1003, and printing layer 1004. Board 1001 is made up of PVC, PET, and synthetic paper and coated with thin magnetic film 1002 of a few micron meter thickness. Protective layer 1003 protects the magnetic film. On printing layer 1004, letters are printed. On the board are another printing layer 1005 on which pictographs are to be printed and protective layer 1006. Magnetic card illustrated in FIG. 120C is commonly used for cash cards, telephone cards, and credit cards, to name a few.
FIG. 121 describes the basic theory of a data read and data write for a magnetic card reader carried in an article of an in-house handbook for using cards issued by one leading company in Japan. In this Figure, feed rollers 1007 and 1008 allow magnetic card 1000 to travel back and forth. Driving motor 1009 spins feed roller 1007 by means of belt 1010. When the driving motor rotates in the direction of arrow A, magnetic card 1000 placed between feed roller 1007 and pressure roller 1011 travels in the direction of arrow B to the position between magnetic head 1012 and head pressure roller 1013.
While magnetic card 1000 passes through magnetic head 1012, data is written onto or read from the magnetic layer 1002 on the magnetic card, which is then sent to feed roller 1008 and pressure roller 1014. Feed roller 1007 and feed roller 1008, both of which are identical in diameter, are linked by means of belt 1015. Thus, the magnetic card travels from feed roller 1007 to feed roller 1008 at a constant speed in the direction of arrow B, and then ejected.
After data recording or reproducing, it is also possible to reverse the motor rotation so as to back travel the magnetic card to be ejected from the insertion slot. Conventionally, two or more magnetic heads read or write data while a magnetic card is traveling in one direction. Therefore the card could store only scores of bytes. Moreover, a user had to insert a magnetic card again into a slot of a magnetic card reader whenever the user wants to re-access the same information.
Several attempts have been made to solve the above-mentioned problems by using a rotation drum found in a video tape recorder or a tape drive for storing data. They embrace a method of reading or writing data with several magnetic heads on a rotation drum by helically scanning a magnetic tape wound on the drum. The magnetic heads are mounted on the circumference of a turntable to form arc tracks on a magnetic storage medium. It is important to note that these methods aim at obtaining non-linear recording tracks, and signals are transmitted to and from magnetic head by means of a rotary transformer.
"THE MAGNETIC CARD READER" introduced in Japan Patent Application Sho 62-194717 set forth the structure that forms tracks with two or more magnetic heads on the turntable. The rotation of a turntable and the move of a carriage on which the turntable and a motor are mounted, are linked by the single motor. It is an improvement that the loci of tracks on a storage medium are not circular but continuous spirals.
"MAGNETIC CARD AND MAGNETIC CARD ISSUER" of Japan Patent Application Sho 63-228212 calls for a method of storing data on a circular track shown in FIG. 122 instead of the striped tracks in FIG. 120C. Data is recorded on a circular track 1017 with magnetic head 1016 on the recording surface of a magnetic card. When a circular track is used and magnetized at a density with 210BPI/75BPI specified by the Japanese Industrial Standard, the track length becomes 1.7 times longer than the conventional striped tracks if the diameter of the circular track is 38 mm. This method is unique in that it employs only one circular track on a magnetic card.
FIG. 123 illustrates a method presented in "DATA CARD READER" of Japan Patent Application Sho 59-66777. The tracks of this invention are arc-shaped and aligned in longitudinal direction of a magnetic card which is the size of an ID card (JISB-9560). On magnetic card 1000 having an effective length of about 80 mm, up to 3,000 arc tracks T-1, T-2, etc. measuring 55 mm in width and 26 micrometer in track width can be stored. The characteristics of this method is that magnetic heads are jumped out of a magnetic card on rear tracks (left edge of the card in FIG. 123).
Japan Patent Application Sho 62-223468 and Japan patent Application Hei 1-218020 also introduced the method of using uni-directional arc tracks as shown in FIG. 123.
FIG. 124 illustrates a method introduced in "THE METHOD OF POSITIONING MAGNETIC CARD FOR MAGNETIC STORAGE DRIVE" of Japan Patent Application Hei 2-24759. The starting track number and the ending track number of arc tracks 1018 are recorded on the header (not shown). By comparing these track numbers, the extent of track deviation is detected. After inserting locking pin 1019 to a hole on one side of the magnetic card, a card is positioned by moving adjustable pins 1020, which are inserted into two holes located on the opposite with locking pin 1019 as the center. Rotation motor 1022 that rotates magnetic head 1021 is located outside of the magnetic card and the magnetic head 1021 is placed outside of the magnetic card when it is not operating.
"MAGNETIC RECORDING CARTRIDGE" of Japan Patent Application Hei 2-157358 purports a magnetic recording cartridge. A carrier mechanism that moves a magnetic card forward and magnetic heads and several supporting arms for the magnetic heads are housed in a single storage case. A large rectangular hole is made in the center of two groups of arc tracks so that a magnetic card will be transported without being hindered by any components such as rotation shaft.
The arc recording tracks makes it possible not only to increase the number of tracks but also to re-access a certain track continuously when compared to conventional striped magnetic card.